In violent intergroup conflicts between chimpanzee groups the hormone oxytocin enhances the social affiliation among members of the same group

The high costs of individuals going to war is perplexing. Individuals are willing to suffer costs in order to benefit their own group, through cooperating and supporting their fellow group members and acting with hostility towards the out-group. Although aggressive, these conflicts are also known to enhance the sense of group belonging and promote social cohesion and affiliation among group members, essential aspects of successful competition with out-groups. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have measured the concentration of the hormone oxytocin in the urine of wild chimpanzees before and during intergroup conflicts and found that their social affiliations enable chimpanzees, too, to stand by each other against rivals.

Findings from Lapa do Santo show oldest evidence in the continent of humans performing elaborated funerary rituals based on the manipulation and reduction of fresh corpses and the reorganization of body parts

In eastern South America skeletal remains dating to 10,000 years ago are rare, precluding the proper study of their ritual dimensions. In a study published this week in the journal Antiquity an international research team led by the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the University of Sao Paulo, Brazil, present their new findings on 26 human burials that date to this period and had been discovered at the archaeological cave site Lapa do Santo in east central Brazil.

Max Planck researchers found chimpanzees routinely fish for algae during the dry season in Bakoun, Guinea, using long and robust sticks as a tool

Chimpanzees often use tools to extract or consume food but which tools they choose for which purpose can differ depending on where they live. In 2010, researchers at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, initiated the ‘Pan African Programme: The Cultured Chimpanzee’ to characterize and understand the differences in chimpanzee behaviours in un- and poorly studied ape populations across Africa. This is how the researchers encountered a new behavioural variant: Algae fishing with long robust tools at a temporary research site in Bakoun, Guinea.

Support from family and friends significantly reduces stress in wild chimpanzees – during conflicts with rival groups and during everyday affiliation

In humans and other social animals stress is associated with poor health and high mortality. These negative effects can be buffered by receiving social support from relatives or friends. However, the mechanisms responsible for this effect remain largely unknown. A team led by Roman Wittig, Catherine Crockford and Tobias Deschner from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, has studied how wild chimpanzees cope with stressful and non-stressful situations when a close bond partner is present or absent. They measured the animals’ urinary stress hormone levels during episodes of intergroup conflict, grooming and resting and found that the support of a friend significantly reduced the chimpanzees’ stress hormone levels, especially in situations of conflict. But even during affiliative activities with the bond partner stress levels were generally lower. Daily supportive actions by friends and family maybe key to regulating stress hormone activity, and thus the negative effects of stress, a finding with potential medical implications for humans.

Archaeologists have created a new database from the teeth of prehistoric humans found at ancient burial sites in Britain and Ireland that tell us a lot about their climate, their diet and even how far they may have travelled. In a paper, led by Maura Pellegrini from the University of Oxford, researchers say that individuals in prehistoric Britain were highly mobile. The international team included researchers of the Max Planck Institute for Evolutionary Anthropology.

October 06, 2016: Apes understand that some things are all in your head

Bonobos, chimpanzees and orangutans understand that others can be convinced of something that is not true

We all know that the way someone sees the world, and the way it really is, are not always the same. This ability to recognize that someone’s beliefs may differ from reality has long been seen as unique to humans. But new research on chimpanzees, bonobos and orangutans suggests our primate relatives may also be able to tell when something is just in your head. The study was led by researchers of Duke University, Kyoto University, the University of St. Andrews and the Max Planck Institute for Evolutionary Anthropology.

Our similarities and differences to chimpanzees, our great ape cousins, have intrigued people for centuries. Of particular interest is the brain. Scientists at the Max Planck Institute of Molecular Cell Biology and Genetics in Dresden (MPI-CBG) and the Max Planck Institute for Evolutionary Anthropology in Leipzig (MPI-EVA) now report the first detailed comparison of how human and chimpanzee stem cells form a cerebral cortex during brain development. They uncover a subtle but intriguing difference in how the cortical stem cells divide – the human cells take more time to arrange the chromosomes before they are distributed to the daughter cells. This may help to understand why human and chimpanzee brains develop differently.

Three-year-olds quickly absorb social norms. They even understand behaviors as rule-governed that are not subject to any norms, and insist that others adhere to these self-inferred “norms”.

In a study, recently published in the journal Psychological Science, Marco F. H. Schmidt, in collaboration with Lucas P. Butler (Assistant Professor at University of Maryland), Julia Heinz and Professor Michael Tomasello (Co-Director at Max Planck Institute for Evolutionary Anthropology, Leipzig), now shows that three-year-olds not only learn social norms from direct instruction and prohibition – as traditionally assumed, but also seek norms themselves – even inferring them where adults see none.

September 26, 2016: Ear ossicles of modern humans and Neandertals - different shape, similar function

Scientists find the greatest number of small ear ossicles known from Neandertals so far and compare them to the ossicles of modern humans

A research team led by scientists of the Max Planck Institute for Evolutionary Anthropology scanned the skulls of Neandertals and found the small middle ear ossicles, which are important for hearing, still preserved within the cavities of the ear. To their surprise, the Neandertal ossicles are morphologically distinct from the ossicles of modern humans. Despite the differences in morphology, the function of the middle ear is largely the same in the two human species. The authors relate the morphological differences in the ossicles to different evolutionary trajectories in brain size increase and suggest that these findings might be indicative of consistent aspects of vocal communication in modern humans and Neandertals. These findings are also of importance for shedding light on the emergence of human spoken language, which can only be inferred indirectly from the archaeological and fossil record.

September 16, 2016: Palaeoproteomics helps differentiate between modern humans and Neandertals

Researchers decode ancient proteins of Châtelperronian Neandertals

The Châtelperronian of central France and northern Spain is critical to the debate regarding Neandertal cognition, their use of artefacts typically associated with modern humans and finally, their extinction. Despite intense research, the exact biological nature of the Châtelperronian people is still disputed and no direct molecular data for a Neandertal association with the Châtelperronian has been obtained. To solve this problem, an international research team utilized recent developments in ancient protein analysis, combined with multiple additional lines of evidence to demonstrate that the Châtelperronian hominins at the Grotte du Renne, an archaeological site from north central France, are Neandertals.

During human development, stem cells differentiate into many different cell types that build and determine the function of complex organs. Previous studies have provided only limited insights into the genetic programs that control organ development. By adapting the methodology of single cell transcriptomics analysis, junior scientist Dr. Barbara Treutlein from the Max Planck Institute for Evolutionary Anthropology in Leipzig for the first time made it possible to perform genome-wide measurements of genetic expression in unprecedented resolution on the single cell level. In her research, she applies this method to understand the genetic foundations of organogenesis, i.e. the process by which cells differentiate into organs, and to make possible their in-vitro recreation under controlled conditions. In her lab, Dr. Treutlein grows hepatic and cerebral organoids and compares them with real organ tissue.

July 27, 2016: Voice control in orangutan gives clues to early human speech

Orangutan Rocky could provide the key to understanding how speech in humans evolved from the time of the ancestral great apes

Previously it was thought that great apes – our closest relatives – could not learn to produce new sounds and because speech is a learned behaviour it could not have originated from them. In an imitation “do-as-I-do” game, eleven-year-old Rocky, who was eight at the time of the research, was able to copy the pitch and tone of sounds made by researchers to make vowel-like calls. The discovery, led by Durham University, UK, shows that orangutans could have the ability to control their voices. Alexander Mielke of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, was part of the international research team.

An international team of researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the Félix Houphouët Boigny University in Abidjan, Ivory Coast were the first to explore an alternative way to gain insight into what nutritional aspects of natural food sources are important and preferred by wild foragers by combining analyses on the ranging patterns of wild chimpanzees. For this, the researchers followed five adult female chimpanzees from Taï National Park, Côte d’Ivoire, for more than 275 days and tested the relationship between the changes in travel direction that occurred on the chimpanzees daily travel paths and the nutritional aspects of the fruit species that they feed on and the trees’ characteristics. They found that chimpanzees were more likely to aim their travel towards fruit-bearing trees belonging to rare tree species and trees that provided fruits with high amounts of fat, sugar and fiber, such as nuts.

1.5-million-year-old footprints provide window to the life of Homo erectus

Fossil bones and stone tools can tell us a lot about human evolution, but certain dynamic behaviours of our fossil ancestors – things like how they moved and how individuals interacted with one another – are incredibly difficult to deduce from these traditional forms of paleoanthropological data. Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig, along with an international team of collaborators, have recently discovered multiple assemblages of Homo erectus footprints in northern Kenya that provide unique opportunities to understand locomotor patterns and group structure through a form of data that directly records these dynamic behaviours. Using novel analytical techniques, they have demonstrated that these H. erectus footprints preserve evidence of a modern human style of walking and a group structure that is consistent with human-like social behaviours.

Sexual swellings are unreliable signals of fertility in female bonobos

In several species of primates, males often discern when to mate with a female based on cyclical changes in the size and firmness of her sexual swelling – a visual signal of a female’s probability to conceive. In a study of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, primatologist Pamela Heidi Douglas and colleagues investigated for the first time the relationship between ovarian hormones and sexual swellings in wild female bonobos. The likelihood that a female bonobo ovulates during her maximum swelling phase is much lower than in the closely related chimpanzees. Swellings are thus no reliable fertility signal for males and allow females to follow their own agenda when choosing a mate.

If a Neandertal were to sit down next to us on the underground, we would probably first notice his receding forehead, prominent brow ridges and projecting, chinless face. Only on closer inspection would we notice his wider and thicker body. Researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig have now investigated whether the differences in physique between Neandertals and modern humans are genetic or caused by differences in lifestyle. Their analysis of two well-preserved skeletons of Neandertal neonates shows that Neandertals’ wide bodies and robust bones were formed by birth.

By analyzing genome-wide data from the remains of 51 humans who lived between 45,000 and 7,000 years ago, an international research team has provided the first vivid look at the genetic history of modern humans in Europe before the introduction of farming. The team’s findings, published May 2 in Nature, reveal the disappearance and reappearance of a group that formed part of the ancestry of today’s Europeans, describe when and how Europeans acquired DNA from people in the Near East and show that the amount of Neanderthal DNA in modern human genomes has shrunk over the millennia, likely because the DNA was evolutionarily disadvantageous.

When it comes to selecting a cooperation partner, information about another person’s reputation – for example as a generous person or a miser – may come handy. Many animal species make reputation judgements, but only humans use gossip to pass on evaluative social information about others. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, show that five-year-olds but not three-year-olds reliably engage in such prosocial gossip.

Tooth-marks on a 500,000-year-old femur from Morocco indicate hominin hunting or scavenging by large carnivores

An international team of researchers including Camille Daujeard of the Muséum National D'Histoire Naturelle in Paris, France, and Jean-Jacques Hublin of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, analyzed tooth-marks on a 500,000-year-old hominin femur bone from a Moroccan cave and found that it had been consumed by large carnivores, likely hyenas.

Researchers find differences between ethnic groups living as farmers and those engaged in traditional hunter-gatherer activities

Scientists have long thought that the rate with which mutations occur in the genome does not depend on cultural factors. The results of a current study suggest this may not be the case. A team of researchers from France and Germany analysed more than 500 sequences of the male Y-chromosome in southern African ethnic groups living as farmers and in population groups engaged in traditional hunter-gatherer activities. The study found that the agriculturalists had a comparatively higher rate of change than the hunter-gatherers did. The researchers explain this by the significantly older average age of paternity among the agriculturalists. Furthermore, the study finds a much older age for the most recent common ancestor of the human Y-chromosome than was previously assumed.

More local adaptations in European genes were contributed by Stone Age hunters than farmers

Modern humans have adapted to their local environments over many thousands of years, but how genetic variation contributed to this adaptation remains debated. Using genomes from humans that lived between 45,000 and 7,000 years ago, researchers from the Max Planck Institute for Evolutionary Anthropology in Leipzig have shown that adaptation to local environments has resulted in genetic variants reaching high frequencies in European groups. Interestingly, most of the adaptive variants were present already in an early hunter-gatherer, but not in an early farmer. This suggests that hunter-gatherers, who lived in Europe for thousands of years before the arrival of farmers, were adapted to local environments and contributed adaptive genetic variants to present-day Europeans.

Analysis of nuclear DNA from Sima de los Huesos hominins provides evidence of their relationship to Neandertals

Previous analyses of the hominins from Sima de los Huesos in 2013 showed that their maternally inherited mitochondrial DNA was distantly related to Denisovans, extinct relatives of Neandertals in Asia. This was unexpected since their skeletal remains carry Neandertal-derived features. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have since worked on sequencing nuclear DNA from fossils from the cave, a challenging task as the extremely old DNA is degraded to very short fragments. The results now show that the Sima de los Huesos hominins were indeed early Neandertals. Neandertals may have acquired different mitochondrial genomes later, perhaps as the result of gene flow from Africa.

More Sumatran orangutans live in the wild than previously thought, yet continuing deforestation is likely to substantially reduce their number

Sumatran orangutans, one of the two existing species of orangutans, live exclusively in the North of the Indonesian island Sumatra and are critically endangered. This great ape is threatened by poaching and forest loss, as its habitat is being converted for agricultural purposes. An international team of researchers has now conducted an extensive series of surveys to estimate the number of Sumatran orangutans and discovered that about 14,600 of these animals still live in the wild today – 8,000 more than previously thought. Good news, however, the increase in numbers is due to a more wide-ranging survey effort and not to an increase in the orangutan population. Moreover, should the deforestation of the orangs’ habitat go ahead as planned, as many as 4,500 individuals could vanish by 2030. The researchers thus urge Sumatran national and provincial legislations to implement measures to avoid negative impacts on forests where orangutans occur.

Chimpanzees often use tools to extract or consume food. Which tools they choose for which purpose, however, can differ depending on the region where they live. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, have thus initiated the ‘Pan African Programme: The Cultured Chimpanzee’ and, since 2010, have collected data on chimpanzee behavior, demography and resource availability across Africa following a standardized protocol. This is how the researchers encountered a thus far unknown behavior: In West Africa chimpanzees throw stones at trees resulting in conspicuous accumulations at these sites. Why exactly the animals do this the researchers do not yet know, yet the behavior appears to have some cultural elements.

Reintroduction of genetically distinct subspecies has led to hybridization in an endangered wild population

As their natural habitats continue to be destroyed, increasing numbers of displaced endangered mammals are taken to sanctuaries and rehabilitation centres worldwide. The ultimate goal of these centres is often reintroduction: to return these animals to wild populations. In a new study published today in Scientific Reports, however, Graham L Banes and Linda Vigilant of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, caution that such reintroductions can act as a form of genetic translocation. By using genetic analysis to assess a subset of historical reintroductions into Tanjung Puting National Park, Indonesia, they found that orang-utans from a non-native and genetically distinct subspecies were unwittingly released and have since hybridized with the Park’s wild population. As orang-utan subspecies are thought to have diverged around 176,000 years ago, with marked differentiation over the last 80,000 years, the researchers highlight the potential for negative effects on the viability of populations already under threat.

Researchers find evolution of human teeth to be much simpler than previously thought, and can predict the sizes of teeth missing from hominin fossils

A new study led by evolutionary biologist Alistair Evans of Monash University in Australia, took a fresh look at the teeth of humans and fossil hominins. The research confirms that molars, including ‘wisdom teeth’ do follow the sizes predicted by what is called ‘the inhibitory cascade’ – a rule that shows how the size of one tooth affects the size of the tooth next to it. This is important because it indicates that human evolution was a lot simpler than scientists had previously thought. The international team included researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany.

February 17, 2016: Early gene flow from modern humans into Neanderthals

Researchers find first genetic evidence of modern human DNA in a Neanderthal individual

Using several different methods of DNA analysis, an international research team has identified an interbreeding event between Neanderthals and modern humans that occurred an estimated 100,000 years ago, which is tens of thousands of years earlier than other such events previously documented. They suggest that some modern humans left Africa early and mixed with Neanderthals. These modern humans later became extinct and are therefore not among the ancestors of present-day people outside Africa who left Africa about 65,000 years ago.

To find energy-rich food, like tropical ripe fruit, is a challenge for chimpanzees

In our supermarkets we buy raspberries in winter and chestnuts in summer. But how challenging would life become, if we needed to consume large amounts of fruit for our daily meal and had to collect them ourselves? With a largely plant-based diet, simple stomachs, and the additional cost of maintaining relatively large brains, chimpanzees face a serious challenge in their daily search for energy and nutrients. Using data on the monthly availability of young leaves, unripe and ripe fruits in three tropical rain forests in East, Central and West Africa, a consortium of researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, Harvard University, McGill University, the University of St. Andrews and the Université Félix Houphouët Boigny, estimated how difficult it is for chimpanzees to find food and to predict its availability in individual trees. This study reports which cognitive strategies chimpanzees can use to gain privileged access to the most energy-rich but ephemeral food.

It almost goes without saying that trust is a defining element of genuine human friendship. Now, researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, suggest that the same holds true among chimpanzee pals. Their findings suggest that friendship based on trust has evolved much earlier than previously thought and is not unique to humans.

The mixing of archaic human forms played an important role in shaping the immune system of modern humans

When modern humans met Neanderthals in Europe and the two species began interbreeding many thousands of years ago, the exchange left humans with gene variations that have increased the ability of those who carry them to ward off infection. This inheritance from Neanderthals may have also left some people more prone to allergies. Researchers of the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, and the Institut Pasteur and the CNRS in Paris, France, report about the discoveries in two independent studies, adding to evidence for an important role for interspecies relations in human evolution and specifically in the evolution of the innate immune system, which serves as the body's first line of defense against infection.